Recent reports have indicated that many xenobiotics (man-made chemicals) in the environment are capable of disrupting the endocrine system not only in a wide variety of animals, but also in human beings. Some of the reported effects in humans include decreased sperm counts and increased cases of testicular cancer and testicular abnormalities, premature puberty in females and increased cases of endometriosis, and an increase in reproductive cancers (13). Perhaps the most well-known example of an endocrine disrupter is DES (diethylstilbestrol), which was administered to pregnant women to prevent premature birth (4). In 1970, an increased incidence of vaginal clear-cell carcinoma was reported in the female offspring of women who had taken DES in the first trimester of pregnancy (5). Since that time, mounting evidence suggests that, in many instances, the presence of certain xenobiotics has had additional deleterious, endocrine-disrupting effects on both human and wildlife populations (6).
The purpose of this position paper is to review current information on the status of endocrine disrupters, with particular emphasis on the implications for environmental and public health. It is intended to be used as a basis from which environmental and public health practitioners and colleagues in related fields can initiate discussions with policy makers at all levels; local, state, national, and worldwide.
Endocrine disrupters, also sometimes called environmental estrogens or estrogenic xenobiotics, influence many developmental and physiological responses at multiple sites of activity (6). Many of the endocrine disrupters discovered to date (Table 1) have an anthropogenic, that is, man-made, source. A major source of these compounds has been found to be sewage, in which approximately 3,000 out of a possible 60,000 man-made organic pollutants have been found (710). In addition to human beings, a number of animal species have also been affected by endocrine disrupters (Table 2). Some of the effects reported include blocking of the effects of male hormones, resulting in the demasculinization of male offspring; antithyroid effects; alterations in the adrenal gland; decreased sperm count in male offspring; structural abnormalities in the external genitalia of female offspring and delayed puberty in the male; defeminization and masculinization of female fish and birds; decreased hatching success in fish, birds, and turtles; decreased fertility in birds, fish, shellfish, and mammals; and gross birth deformities in birds, fish, and turtles (1118).The number of chemicals, or their degradation products, being recognized as endocrine disrupters is rapidly increasing. It should also be noted that synergistic activation of some combinations of chemicals has been reported (19). To a great extent, the consequences of exposure to these compounds is unknown; however, they could have a deleterious effect on physiological processes, particularly reproduction. Further, it is currently unclear what relationship environmental exposure to these compounds may have to either the initiation or progression of certain diseases.
Method of Implementation
Upon adoption, the National Environmental Health Association (NEHA) should disseminate this paper as widely as possible by release to the membership, publication in the Journal of Environmental Health, provision of copies of this paper to affiliates to share with their members, and provision of copies of this paper to similar professional associations for their review. Affiliates and members should be encouraged to provide comments to legislators based on the information contained herein, or to provide a copy of this document as augmentation to their own comments.
The committee foresees the only fiscal impact on NEHA with the adoption of this paper to be the cost of making and mailing copies. The fiscal impact of the problem will be felt mainly by those individuals who suffer from the adverse effects of exposure to endocrine disrupters.
(Original paper prepared by Ginger L. Gist, Ph.D., D.A.A.S., Senior Environmental Health Scientist, Agency for Toxic Substances and Disease Registry.)
Examples of Known and Potential Endocrine Disrupters
|Polychlorinated dibenzo-p-dioxins||33||Polychlorinated dibenzofurans||33|
Examples of Species That Have Been Affected by Endocrine Disrupters
|Nassarius obsoletus||Mud snail||35, 36|
|Larus occidentalis||Western gull||37-39|
|Sterna caspia||Caspian tern||40|
|Larus argentatus||Herring gulls||41|
|Nucella lapillus||Dog whelk||42-44|
|Gambusia affinis holbrookii||Mosquito fish||45-48|
|Catostomis commersoni||White sucker fish||49|
|Ardea herodias||Great blue heron||51|
|Oncorhynchus spp.||Pacific ocean salmon||52|
|Urospinax cinerea||American oyster drill||53|
|Homo sapiens||Human being||54-59|
|Asteria rubens||Sea stars||28|
|Parophrys vetulus||English sole||60|
|Gadus morhua||Atlantic cod||61|
|Pseudopleuronectus americanus||Winter flounder||26|
|Micropogonias undulatus||Atlantic croaker||30|
|Halichoerus grypus||Grey seal||31|
|Phoca groenlandica||Harp seal||63|
|Mytilis edulis L.||Mussel||64|
|Strongylocentrotus intermedius||Sea urchin||66, 67|
|Nucella spp.||Shoreline whelks||68-70|
|Phoca vitulina||Common seal||71|
|Phoca hispida||Baltic ringed seal||72|
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3. Henderson, B.E., L. Bernstein, and R. Ross (1988), "Estrogens as a Cause of Human Cancer: The Richard and Linda Rosenthal Foundation Award Lecture," Cancer Research, 48:246-253.
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5. Herbst, A.L., and H.A. Bern, eds. (1981), Developmental Effects of Diethylstilbestrol (Des) in Pregnancy, New York: Thieme-Stratton.
6. Jobling, S., M.G. Parker, T. Reynolds, J.P. Sumpter, and R. White (1995), "A Variety of Environmentally Persistent Chemicals, Including Some Phthalate Plasticizers, Are Weakly Estrogenic," Environmental Health Perspectives, 103:582-587.
7. Purdom, C.E., V.J. Bye, N.C. Eno, P.A. Hardiman, J.P. Sumpter, and C.R. Tyler (1994), "Estrogenic Effects of Effluents from Sewage Treatment Works," Chemical Ecology, 8:275-285.
8. Donaldson, W.T. (1977), "Trace Organics in Water," Environmental Science Technology, 11:348-351.
9. Bedding, N.D., J.N. Lester, A.E. McIntyre, and R. Perry (1982), "Organic Contaminants in the Aquatic Environment 1: Sources and Occurrence," Science of the Total Environment, 25:143-167.
10. Kraybill, H.F. (1981), "Carcinogenesis of Synthetic Organic Chemicals in Drinking Water," Journal of the American Water Association, 73:370-372.
11. Gray, L.E. Jr., W. Kelce, and J.S. Otsby, "Antiandrogenic Effects of the Fungicide Vinclozolin on Sex Differentiation of the Rat," Toxicology and Applied Pharmacology.
12. O'Neil, W.M., and W.D. Marshall (1984), "Goitrogenic Effects of Ethylenethiourea on Rat Thyroid," Pesticides and Biochemical Physiology, 21:92-101.
13. Rehnberg, G.L., K.C. Booth, R.L. Cooper, J.M. Goldman, L.E. Gray, J.F. Hein, and W.K. McElroy (1988), "Effect of Linuron on The Brain-Pituitary-Testicular Reproductive Axis in the Rat," Toxicologist, 8:121.
14. Colby, H.D. (1988), "Adrenal Gland Toxicity: Chemically Induced Dysfunction," Journal of the American College of Toxicology, 7:45-69.
15. Peterson, R.E., G.L. Kimmel, and H.M. Theobald (1993), "Developmental and Reproductive Toxicity of Dioxins and Related Compounds: Cross-Species Comparisons," Critical Review of Toxicology, 23:283-335.
16. Gray, L.E. Jr., L.S. Birnbaum, W. Kelce, E. Monosson, and J.S. Ostby, "Perinatal TCDD Reduces Ejaculated and Epididymal Sperm Counts in Rats and Hamsters, But Does Not Affect Testosterone or Androgen Receptor Levels," Toxicology and Applied Pharmacology.
17. Gray, L.E. Jr., L.S. Birnbaum, J.J. Diliberto, W. Kelce, R. Marshall, and J.S. Otsby (1993), "Perinatal TCDD Exposure Alters Sex Differentiation in Both Female and Male LE Hooded Rats," Chemosphere, 14:337-340.
18. Colborn, T., and C. Clement, eds. (1992), Consensus Statement. Chemical ly Induced Alterations in Sexual and Functional Development: The Wildlife/Human Connection. Princeton, N.J.: Princeton Scientific Publishing Co., pp. 1-8.
19. Arnold, S.F., B.M. Collins, L.J. Guillette, D.M. Klotz, , and J.A. McLachlan, and P.M. Vonier (1996), "Synergistic Activation of Estrogen Receptor with Combinations of Environmental Chemicals," Science, 272:1489-1492.
In response to one of the biggest health scares of the 1990's, last year federal legislators passed amendments to the Safe Drinking Water Act and the Food Quality Protection Act.
The scare: Increased reports worldwide of altered endocrine function, such as lowered sperm counts and reproductive abnormalities caused by chemicals, termed "endocrine disrupters."
One study that initiated the greatest concern was from Tulane University in 1996 that suggested a 1,600-fold increase in risk of endocrine disruption when relatively small amounts of chemicals were combined. But, as has become true with other alarming reports, this scare may not be real after all.
In the July 25, 1997 issue of Science magazine, Dr. John A. McLachlan, one of the authors of the Tulane study, formally withdrew his original paper, stating "any conclusions drawn from this paper must be suspended until such time, if ever, the data can be substantiated."
In fact, other scientists around the globe have not been able to duplicate the Tulane study. Dr. Stephen Safe, professor of toxicology at Texas A & M University commented: "It is clear that the best science now points to the conclusion that the endocrine effects of environmental chemicals are less harmful than had been suggested."
The scientific investigation continues. The EPA's Endocrine Disrupter Screening and Testing Advisory Committee will still develop and implement a screening program for EPA to submit to Congress by August 1999, and the National Academy of Sciences study is scheduled to be released at the end of . According to Assistant EPA Administrator, Lynn Goldman, "The retraction does not eliminate the scientific basis for regulatory concern over endocrine-disrupting chemicals. Scientific and regulatory realities are not that simple." It appears that the endocrine disrupters scare may have just been the latest example of placing too much emphasis on one study.
(Source: Food Insight, September/October 1997)